msgjd
Well-known member
- 1,112
- 3,414
- 113
- Location
- upstate ny
Hello all, keyword searches did not yield anything specific .. Am looking to add a spin-on ahead of the OEM canister without altering the original lines, need to keep this particular M817 original and uncut for a quick return back to OEM when we are done with a project's numerous upcoming hauls..
Unless the brass fitting assortment at the heavy truck shop near here is totally messed up, the compression nut at the canister end of the fuel tank line is not a normal 1/2" comp fitting as it may appear. 1/2" comp is too small, 3/4 way too big. JIC doesn't work either.
1: Just my luck this might be an Ermeto-type/specialty-size nut on the fuel line to the canister. Can anyone confirm?
2: What is the size/thread of the canister inlet? (where the locknut/o-ring vent fitting goes)
It is bigger than 1/2NPT of course, also obviously smaller than 3/4, and is apparently a straight-thread type, they are not showing any NPT features. I am unaware if 5/8 straight pipe thread was ever made at any point in decades past, clearly it is not available today. Again, these are not NPT type. Nor are they JIC. But possibly SAE. For new knowledge to some out there, the straight pipe threads I am talking about are designated NPSC = National Pipe Straight Coupling, and generically referred to as "IPS Threads" or "Iron Straight Threads"
Unless the brass fitting assortment at the heavy truck shop near here is totally messed up, the compression nut at the canister end of the fuel tank line is not a normal 1/2" comp fitting as it may appear. 1/2" comp is too small, 3/4 way too big. JIC doesn't work either.
1: Just my luck this might be an Ermeto-type/specialty-size nut on the fuel line to the canister. Can anyone confirm?
2: What is the size/thread of the canister inlet? (where the locknut/o-ring vent fitting goes)
It is bigger than 1/2NPT of course, also obviously smaller than 3/4, and is apparently a straight-thread type, they are not showing any NPT features. I am unaware if 5/8 straight pipe thread was ever made at any point in decades past, clearly it is not available today. Again, these are not NPT type. Nor are they JIC. But possibly SAE. For new knowledge to some out there, the straight pipe threads I am talking about are designated NPSC = National Pipe Straight Coupling, and generically referred to as "IPS Threads" or "Iron Straight Threads"
Last edited:
